Question

数学高手来来来！！！初一数学先化简再求值

9x+6x²-3(x-2/3x²）其中x=-1 (2)1/2(2x-6x-4)-4(-1+x+1/4x²)其中x=5

Answer 1

1、=9x+6x^2-3x=2x^2
=8x^2+6x
当x=1时，8x^2+6x=14
2、=1/2(-4x-4)-4(x-1+1/4x^2)
=-2x-2-2x+4-x^2
=-x^2-6x+2
当x=5时，x^2-6x+2=-53

希望采纳~~

Answer 2

1、=9x+6x^2-3x=2x^2
=8x^2+6x
当x=1时，8x^2+6x=14
2、=1/2(-4x-4)-4(x-1+1/4x^2)
=-2x-2-2x+4-x^2
=-x^2-6x+2
当x=5时，x^2-6x+2=-53

Answer 3

解1:=9+6-3(-1/3)
=9+6+1
=16

2:-12 1/100

Answer 4

9x+6x²-3(x-2/3x²）=9x+6x²-3x+2x²=6x+8x²=x(6+8x)然后再代入x=-1就是-1x(6-8)=2
1/2(2x-6x-4)-4(-1+x+1/4x²)=-2x-2+4-4x-x²=-6x+2-x²=-x(6+x)+2把x=5代入就是-5x(6+5)+2=-53

Answer 5

1、先把括号给拆开，原式=9X+6X^2-3X+2X^2=6X+8X^2,再将X=-1代入，得原式=2
2、同样是先拆括号再代入，原式=X-3X-2+4-4X-X^2=-6X-2-X^2=-57

Answer 6

1.6x+8x^2=6*(-1)+8*1=2 2.-2x-2+4-4x-x^2=-6x+2-x^2=-30+2-25=-53.